The present invention relates to resin encapsulated semiconductor elements, which can be improved significantly to increase their reliability when at a high temperature, and to enhance their humidity resistance by encapsulating the semiconductor element with a thermosetting resin composition containing at least an organic compound selected from the group consisting of organobromine compounds, organophosphorus compounds and organonitrogen compounds, and metal borates, and to a process for manufacturing the same.
The semiconductor elements, such as a transistor, IC, LSI, and the like, are mainly encapsulated with a resin using a plastic package to facilitate mass production. As a semiconductor encapsulating material, a resin composition containing an epoxy resin and a phenol resin hardener is most commonly used, because the resin composition is superior in providing a preferable reliability and provides desirable balance among moldability, moisture absorbing resistance and adhesion.
In order to add flame resistance to the properties of the semiconductor encapsulating material, a brominated organic compound, such as a brominated epoxy resin or brominated phenol resin, and an antimonic compound serving as a flame resisting assistant agent are mixed into the encapsulating material.
It has been well known hitherto that the brominated organic compound and the antimonic compound contained in the encapsulating material exert an undesirable influence on the reliability of the semiconductor elements. A junction between the aluminum wiring pad and a gold wire in a semiconductor element has exhibited the problem that breakage of the wire is caused by corrosion, which is enhanced by the release of bromine from the organobromine compound at a high temperature. Particularly, the problem is significant in semiconductor elements in electronic apparatus of the type used in an automobile engine room or in an environment at a high temperature. Furthermore, the released bromine itself enhances corrosion of the aluminum wiring in the semiconductor element, although it may be not so significant as chlorine, and this can be a reason for the decrease in the moisture resistance of the semiconductor element. The above-mentioned problems are caused not only by the organobromine compound, but also by the antimonic compound of the flame resisting assistant agent.
Because the antimonic compound generates antimony bromide gas, it operates to enhance the release of bromine. For this reason, a semiconductor encapsulating material, which can satisfy both satisfactory flame resistance and reliability of the semiconductor elements has been strongly required.
In order to increase the reliability of the semiconductor elements, the suppressing of the release of bromine under conditions of high humidity and high temperature, the trapping the released bromine, and the adopting of a method for making the device flame resistance using with non-halogen group compounds have been proposed.
As a method for suppressing the release of bromine, a brominated epoxy resin having a high thermal stability was proposed, and an encapsulating material containing brominated bisphenol A type epoxy resin, wherein bromine was arranged at a metha position, was disclosed in JP-A-5-320319 (1993). An inorganic ion exchanger of an inorganic hydrotalcite group disclosed in JP-A-4-48759 (1992) and JP-A-6-53789 (1994) has been mixed in the encapsulating material. As method of making the device flame resistant using non-halogen group compounds, solely mixing a flame retardant the red phosphorus group has been disclosed in JP-A-7-157542 (1995) and JP-A-7-173372 (1995), and solely mixing a boron compound has been disclosed in JP-A-6-107914 (1994).
Furthermore, a concurrent use of at least two kinds of non-halogen group flame retardants selected from the group consisting of phenol resin, phosphorus or red phosphorus, nitrogen, boron compounds and metal hydrides has been disclosed in JP-A-7-331033 (1995) and JP-A-8-151505 (1996).